Spontaneous reporting of adverse events following pandemic influenza A (H1N1) immunization in a reference center in the State of Sao Paulo, Brazil

Abstract

Introduction: This paper describes adverse events (AEs) temporally associated to the pandemic influenza A (H1N1) vaccine observed in a reference center in So Paulo, Brazil, during a 2010 mass vaccination campaign. Methods: A retrospective study involving persons who sought medical care for AEs following influenza vaccination. Data were retrieved from medical records, vaccine AE notification forms, and a computerized system for immunobiological registration. Results: Sixty-six vaccinees sought medical care for AEs after immunization. The most frequent AEs were fever, headache, myalgia, and pain at the injection site. No serious AEs were reported. Conclusions: Few vaccinees spontaneously reported AEs to influenza A (H1N1) vaccine at this center.